Vehicle manufactures produce a range of vehicle power plants including internal combustion engines. An internal combustion engine compresses and ignites a fuel and air mixture to produce engine power. If the mixture fails to ignite and/or completely burn, the incomplete combustion may be considered an engine misfire. Engine misfires can cause engine component damage or can produce unwanted emissions.
Engine speed information from a crankshaft position sensor can be used to detect engine misfires. Speed variation of a crankshaft is measured throughout the travel of a piston in a specific cylinder during a combustion event. Multiple combustion events for each cylinder are then compared to determine if a misfire has occurred. Inaccuracies, however, can occur when trying to detect engine misfires. The inaccuracies can be due to torque resonance of the crankshaft, drive line induced speed fluctuations and increased engine speed variability around an idle engine speed. Moreover, engine speed data is typically collected for each cylinder throughout the complete travel of its respective piston. The inaccuracies and voluminous data may decrease a misfire signal to noise ratio in an engine control. Undetected misfires can lead to possible engine damage and/or unwanted emissions. Falsely detected misfires can lead to unnecessary warranty costs.